Foraminiferal sandy contourite of the Limpopo Corridor (Mozambique margin): Facies characterization and paleoceanographic record

Contourites encompass a wide variety of sedimentary facies. Some of them show common facies with others deep-water deposits, such as turbidites and hemipelagites. Sedimentological characterization at macro- and microscales is valuable to discriminate those close facies but the distinction is not alw...

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Bibliographic Details
Published in:Marine Geology
Main Authors: Lopes, U., Babonneau, Nathalie, Fierens, R., Revillon, Sidonie, Raisson, F., Miramontes, E., Rabineau, Marina, Aslanian, Daniel, Moulin, Maryline
Other Authors: Geo-Ocean (GEO-OCEAN), Université de Bretagne Sud (UBS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)
Format: Article in Journal/Newspaper
Language:English
Published: HAL CCSD 2023
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Online Access:https://hal.science/hal-04204027
https://hal.science/hal-04204027/document
https://hal.science/hal-04204027/file/Revised%20paper%20without%20changes-HAL.pdf
https://doi.org/10.1016/j.margeo.2023.107031
Description
Summary:Contourites encompass a wide variety of sedimentary facies. Some of them show common facies with others deep-water deposits, such as turbidites and hemipelagites. Sedimentological characterization at macro- and microscales is valuable to discriminate those close facies but the distinction is not always clear. Contourites are increasingly used in paleoceanographic and paleoclimatic reconstructions. Improving their characterization is therefore essential to their interpretations.This study aims at characterizing a foraminiferal sandy contourite facies from a sediment core collected on top of a contourite drift under the influence of the Antarctic Intermediate Water/North Atlantic Deep-Water interface located in the Limpopo Corridor (Mozambique margin, Indian Ocean) at 2000 m depth. This work is based on a detailed analysis of the sedimentary record using physical properties (gamma density and magnetic susceptibility) as well as laser grain size and X-Ray Fluorescence core scanning data.Our results show that: (1) the foraminiferal sand is vertically continuous and homogenous over 633 kyr with an average sedimentation rate of 0.26 cm.kyr−1; (2) this contourite facies results from sedimentation with low terrigenous inputs under stable hydrodynamic conditions over time, with relatively strong bottom currents for this water depth (∼16 cm.s−1); (3) during glacial stages, sedimentation rates are lower and bottom current speed is higher than during interglacial stages. We also propose the concept of “Contourite Graphical Chart” which summaries the theoretical distribution of contourite endmembers from cross-plot of “sorting versus grain-size median D50” and their related sedimentary processes.This study highlights the relevance of condensed foraminiferal sandy contourites as long time-scale paleoceanographic archives and provides new insights for studies related to paleoclimatology and paleoecology.